Pathogens such as bacteria, parasites, toxins, and viruses have emerged as public health problems. Worldwide, pathogenic infections are responsible for more deaths than any other cause. At times, the pathogens are opportunistic when our resistance is low due to Acquired Immuno Deficiency Syndrome (AIDS), immunosuppressive drug therapy, anticancer treatment or other related factors. Food borne disease outbreaks, emergence of newer strains of drug-resistant bacterial pathogens without any forewarning (such as the recent outbreak of Severe Acute Respiratory Syndrome (SARS) in Asia), Bird Flu, or pathogens used as a potentially viable source of biological warfare weapons for mass destruction, necessitate the development of a rapid, portable, analytical device as an early warning system for real-time detection of bacterial pathogens in field conditions.
U.S. Pat. No. 6,180,335 discloses a flow-through assembly for the detection of bacterial contamination in the food processing industry. The content of U.S. Pat. No. 6,180,335 is incorporated by reference herein. The disposable element disclosed in the patent includes an immunosorbent layer having antibodies to a target microbe affixed thereto, a membrane or carbon powder in support of the immunosorbent layer, and three electrodes for detecting electrochemical signals. The disposable element may be used to measure the level of microbiological contamination in a solid sample caused by a predetermined microbe. This disposable sensor element cannot be used as a commercial product. However, the U.S. Pat. No. 6,180,335 is directed to the detection of food contaminations. The disposable element disclosed therein contains a pre-filter, three ports, and at least one electrode, all of which increase the size of the disposable element and add unnecessary costs to the assay. Further, in the patent, the filtration membrane used in support of the immunosorbent layer is not conductive, necessitating the presence of an electrode in close proximity to the membrane in order to accurately measure the changes in electron transfer.
The bulky sensor element as shown in FIG. 1 needs continuous replenishment of Ag/AgCl electrode and chlorinization. Also the carbon working electrodes must be cleaned. Therefore a disposable element needs to be developed, designed, and tested. For commercialization we need a disposable sensor with Antigen or Antibodies immobilized so any analytes could be readily tested.